s390/scm_block: allocate aidaw pages only when necessary
AOBs (the structure describing the HW request) need to be 4K
aligned but very little of that page is actually used. With
this patch we place aidaws at the end of the AOB page and only
allocate a separate page for aidaws when we have to (lists of
aidaws must not cross page boundaries).
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/scm_blk.c b/drivers/s390/block/scm_blk.c
index 5b2abad..f5c369c 100644
--- a/drivers/s390/block/scm_blk.c
+++ b/drivers/s390/block/scm_blk.c
@@ -121,7 +121,8 @@
u64 aidaw = msb->data_addr;
unsigned long flags;
- if ((msb->flags & MSB_FLAG_IDA) && aidaw)
+ if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
+ IS_ALIGNED(aidaw, PAGE_SIZE))
mempool_free(virt_to_page(aidaw), aidaw_pool);
spin_lock_irqsave(&list_lock, flags);
@@ -134,26 +135,47 @@
return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
}
-struct aidaw *scm_aidaw_alloc(void)
+static inline struct aidaw *scm_aidaw_alloc(void)
{
struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
return page ? page_address(page) : NULL;
}
+static inline unsigned long scm_aidaw_bytes(struct aidaw *aidaw)
+{
+ unsigned long _aidaw = (unsigned long) aidaw;
+ unsigned long bytes = ALIGN(_aidaw, PAGE_SIZE) - _aidaw;
+
+ return (bytes / sizeof(*aidaw)) * PAGE_SIZE;
+}
+
+struct aidaw *scm_aidaw_fetch(struct scm_request *scmrq, unsigned int bytes)
+{
+ struct aidaw *aidaw;
+
+ if (scm_aidaw_bytes(scmrq->next_aidaw) >= bytes)
+ return scmrq->next_aidaw;
+
+ aidaw = scm_aidaw_alloc();
+ if (aidaw)
+ memset(aidaw, 0, PAGE_SIZE);
+ return aidaw;
+}
+
static int scm_request_prepare(struct scm_request *scmrq)
{
struct scm_blk_dev *bdev = scmrq->bdev;
struct scm_device *scmdev = bdev->gendisk->private_data;
- struct aidaw *aidaw = scm_aidaw_alloc();
struct msb *msb = &scmrq->aob->msb[0];
struct req_iterator iter;
+ struct aidaw *aidaw;
struct bio_vec bv;
+ aidaw = scm_aidaw_fetch(scmrq, blk_rq_bytes(scmrq->request));
if (!aidaw)
return -ENOMEM;
- memset(aidaw, 0, PAGE_SIZE);
msb->bs = MSB_BS_4K;
scmrq->aob->request.msb_count = 1;
msb->scm_addr = scmdev->address +
@@ -188,6 +210,8 @@
scmrq->bdev = bdev;
scmrq->retries = 4;
scmrq->error = 0;
+ /* We don't use all msbs - place aidaws at the end of the aob page. */
+ scmrq->next_aidaw = (void *) &aob->msb[1];
scm_request_cluster_init(scmrq);
}